High pressure gas storage

ABSTRACT

A storage wellhead allowing on-line system maintenance and testing is provided. Including at least two fluidically parallel gas passages adapted to allow testing or maintenance of one gas passage, while the other gas passage remains in service. The gas may be hydrogen. Also including at least two fluidically parallel liquid passages adapted to allow testing or maintenance of one liquid passage, while the other liquid passage remains in service. The liquid may be brine.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No. 14/303,304 filed Jun. 12, 2014, the entire contents of which are incorporated herein by reference.

BACKGROUND

The storage of gases in very deep caverns, whether leached in salt formations or created by hard rock mining, or other gas storage at high pressure conditions require equipment rated for that pressure. Regulatory statues require periodic function testing of emergency control valves and safety equipment. Commercial demand requires continuous flow of gas from the storage cavern, thus creating the need for multiple flow paths from the storage cavern.

SUMMARY

A storage wellhead allowing on-line system maintenance and testing is provided. Including at least two fluidically parallel gas passages adapted to allow testing or maintenance of one gas passage, while the other gas passage remains in service.

The gas may be hydrogen. Also including at least two fluidically parallel liquid passages adapted to allow testing or maintenance of one liquid passage, while the other liquid passage remains in service. The liquid may be brine.

BRIEF DESCRIPTION OF THE FIGURES

For a further understanding of the nature and objects for the present invention, reference should be made to the following detailed description, taken in conjunction with the accompanying drawings, in which like elements are given the same or analogous reference numbers and wherein:

FIG. 1 illustrates one embodiment of the present invention.

FIG. 2 illustrates another embodiment of the present invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

Illustrative embodiments of the invention are described below. While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.

It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developer's specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure.

For the purpose of this invention, the definition of high pressure is defined as a gas storage pressure at or above 2401 psig.

This invention claims the design of the storage wellhead for high pressure gas to include two outlets on both the gas and the liquid wellhead spools to facilitate testing and maintenance of valves so as to not interrupt gas or liquid flow. For gas storage pressures of 2401 psig to 4000 psig, all flanges and valves meet API 5000 (API 5M) and for gas storage pressures of 4001 psig to 8000 psig, all flanges and valves meet API 10000 (API 10M).

This invention further claims that the wellhead design includes hydraulically operated valves of the required pressure rating for use as emergency shutdown devices (ESDs) on the high pressure gas and brine systems. The piping size of the hydraulically operated valves can be from 2 inch up to 9 inch. The protection of brine and water systems which operate at lower pressure require an additional automatic valve in the line to create a double block on the brine out of the storage well. All automated valves in this invention are designed to fail closed on loss of signal, loss of hydraulic pressure, and on loss of instrument gas.

This invention further claims that the liquid master valve, high pressure gas wing valves, brine wing valves, and brine logging valve design includes the use of manual valves of the required pressure rating. The piping size of the manually operated valves can be from 2 inch up to 9 inch.

This invention further claims that each wellhead spool has a flange connection for pressure indication.

Turning to FIGS. 1 and 2, a storage wellhead allowing on-line system maintenance and testing is described. Within a gas wellhead spool (117) is a gas passage (102) and a liquid passage (101). As the gas passage (102) penetrates the gas wellhead spool (117), it splits into at least two fluidically parallel gas passages (103,104). The gas wellhead spool (117) is adapted to allow testing or maintenance of one gas passage (103,104), while the other gas passage remains in service.

The storage wellhead may be designed such that each gas passage (103, 104) is capable of conveying the entire design gas flowrate. The gas may be hydrogen. Each gas passage may comprise an automatic gas valve (107,108). Each gas passage (103, 104) may comprise a gas wing valve (105, 106). After passing through the gas passage (103, 104), the gas wing valve (105, 106), and the automatic gas valve (107, 108), the gas exits the storage wellhead through conduit (109), to be utilized downstream.

As illustrated in FIG. 1, during normal operation, which is to say under non-testing conditions, all gas passages (103, 104), automatic gas valve (107, 108), and gas wing valves (105, 106) may remain in service. FIG. 2 illustrates the situation where one automatic gas valve (107) is closed, as would be the case during testing, while simultaneously the other automatic gas valve (108) is open and allowing gas to pass.

As the liquid passage (101) penetrates the gas wellhead spool (117), it splits into at least two fluidically parallel liquid passages (110,111), wherein the liquid wellhead spool (118) is adapted to allow testing or maintenance of one liquid passage (110, 111), while the other liquid passage remains in service. The storage wellhead may be designed such that each liquid passage (110, 111) is capable of conveying the entire design liquid flowrate. The liquid may be brine. Each liquid passage may comprise an automatic liquid valve (114,115). Each liquid passage (110, 111) may comprise a liquid wing valve (112, 113). After passing through the liquid passage (110, 111), the liquid wing valve (112, 113), and the automatic liquid valve (114, 115), the liquid exits the storage wellhead through conduit (116), to be utilized downstream.

As illustrated in FIG. 1, during normal operation, which is to say under non-testing conditions, all liquid passages (110, 111), automatic liquid valve (114, 115), and liquid wing valves (112, 113) may remain in service. FIG. 2 illustrates the situation where one automatic liquid valve (115) is closed, as would be the case during testing, while simultaneously the other automatic gas valve (114) is open and allowing gas to pass.

The gas passage (103, 104), or automatic gas valve (107,108), testing may occur at predefined first intervals. The predefined first interval may be once a month. The liquid passage (110,111), or automatic liquid valve (114,115), testing may occur at predefined second intervals. The predefined second interval may be once a month.

The gas wellhead spool may operate at a pressure of greater than 2400 psig. The gas wellhead spool may operate at a pressure of less than 4000 psig. The gas wellhead spool may operate at a pressure of less than 3000 psig.

All automatic gas valves (107,108) and all automatic liquid valves (114,115) may be tested at a predefined third interval. The predefined third interval may be every six months. The automated valves may be hydraulically operated.

The test may comprise measuring the time for each valve to move from a fully open position to a fully closed position.

The liquid wellhead spool may operate at a pressure of greater than 2400 psig. The liquid wellhead spool may operate at a pressure of less than 4000 psig. The liquid wellhead spool may operate at a pressure of less than 3000 psig.

It will be understood that many additional changes in the details, materials, steps and arrangement of parts, which have been herein described in order to explain the nature of the invention, may be made by those skilled in the art within the principle and scope of the invention as expressed in the appended claims. Thus, the present invention is not intended to be limited to the specific embodiments in the examples given above. 

1-15. (canceled)
 16. A method of on-line system maintenance and testing of a storage wellhead, comprising performing testing or maintenance on a first fluidically parallel and interchangeable hydrogen passage of a hydrogen wellhead spool passages while a second fluidically parallel and interchangeable hydrogen passage of the hydrogen wellhead spool simultaneously remains in service, or performing testing or maintenance on a first fluidically parallel and interchangeable brine passage of a brine wellhead spool while a second fluidically parallel and interchangeable brine passage of the brine wellhead spool simultaneously remains in service.
 17. The method of claim 16, wherein the hydrogen passage testing occurs at predefined first intervals.
 18. The method of claim 17, wherein the predefined first interval is once a month.
 19. The method of claim 16, wherein the brine passage testing occurs at predefined second intervals.
 20. The method of claim 19, wherein the predefined second interval is once a month.
 21. The method of claim 16, wherein the hydrogen wellhead spool operates at a pressure of greater than 2400 psig.
 22. The method of claim 21, wherein the hydrogen wellhead spool operates at a pressure of less than 4000 psig.
 23. The method of claim 22, wherein the hydrogen wellhead spool operates at a pressure of less than 3000 psig.
 24. The method of claim 16, wherein the brine wellhead spool operates at a pressure of greater than 2400 psig.
 25. method of claim 24, wherein the brine wellhead spool operates at a pressure of less than 4000 psig.
 26. The method of claim 25, wherein the brine wellhead spool operates at a pressure of less than 3000 psig. 